Merge pull request #5 from KyberNetwork/feat/estimate-gas-bundle

feat: estimate gas bundle

eth/api_simulation.go

@@ -13,6 +13,11 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/eth/ethconfig"
+	"github.com/ethereum/go-ethereum/eth/gasestimator"
+	"github.com/ethereum/go-ethereum/internal/ethapi"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/consensus/misc/eip1559"
 	"github.com/ethereum/go-ethereum/rpc"
@@ -30,6 +35,8 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 )
 
+const estimateGasErrorRatio = 0.015
+
 var (
 	enableDevnet = os.Getenv("ENABLE_DEVNET")
 )
@@ -51,9 +58,34 @@ type CallBundleArgs struct {
 	BaseFee                *big.Int              `json:"baseFee"`
 }
 
+type EstimateGasBundleArgs struct {
+	Transactions []ethapi.TransactionArgs `json:"transactions"`
+}
+
+type revertError struct {
+	error
+	reason string // revert reason hex encoded
+}
+
+// This function is copied from
+// https://github.com/KyberNetwork/geth/blob/6b0de79935110fb5f63a60288191848dd98980ea/internal/ethapi/errors.go#L46
+func newRevertError(revert []byte) *revertError {
+	err := vm.ErrExecutionReverted
+
+	reason, errUnpack := abi.UnpackRevert(revert)
+	if errUnpack == nil {
+		err = fmt.Errorf("%w: %v", vm.ErrExecutionReverted, reason)
+	}
+	return &revertError{
+		error:  err,
+		reason: hexutil.Encode(revert),
+	}
+}
+
 type Backend interface {
 	BlockChain() *core.BlockChain
 	TxPool() *txpool.TxPool
+	Config() *ethconfig.Config
 }
 
 var (
@@ -474,3 +506,56 @@ func (b *SimulationAPIBackend) CallBundle(ctx context.Context, args CallBundleAr
 	ret["bundleHash"] = "0x" + common.Bytes2Hex(bundleHash.Sum(nil))
 	return ret, nil
 }
+
+func (b *SimulationAPIBackend) EstimateGasBundle(ctx context.Context, args EstimateGasBundleArgs, overrides *ethapi.StateOverride) ([]uint64, error) {
+	txs := args.Transactions
+
+	if b.stateDb == nil {
+		return nil, fmt.Errorf("statedb is empty")
+	}
+
+	if b.currentBlock == nil {
+		return nil, fmt.Errorf("current block is empty")
+	}
+
+	var (
+		stateDB     = b.stateDb.Copy()
+		parent      = b.currentBlock.Header()
+		chainConfig = b.eth.BlockChain().Config()
+		gasCap      = b.eth.Config().RPCGasCap
+
+		opts = &gasestimator.Options{
+			Config:           chainConfig,
+			Chain:            b.eth.BlockChain(),
+			Header:           parent,
+			State:            stateDB,
+			IsNotCopyStateDB: true,
+			ErrorRatio:       estimateGasErrorRatio,
+		}
+	)
+	if err := overrides.Apply(stateDB); err != nil {
+		log.Error("Failed to apply overrides to state db", "err", err)
+		return nil, err
+	}
+
+	var gasEstimatedBundles []uint64
+
+	for _, tx := range txs {
+		// Run the gas estimation andwrap any revertals into a custom return
+		call, err := tx.ToMessage(gasCap, parent.BaseFee)
+		if err != nil {
+			return nil, err
+		}
+		estimate, revert, err := gasestimator.Estimate(ctx, call, opts, gasCap)
+		if err != nil {
+			if len(revert) > 0 {
+				return nil, newRevertError(revert)
+			}
+			return nil, err
+		}
+
+		gasEstimatedBundles = append(gasEstimatedBundles, estimate)
+	}
+
+	return gasEstimatedBundles, nil
+}

eth/backend.go

@@ -495,6 +495,9 @@ func (s *Ethereum) SyncMode() downloader.SyncMode {
 	mode, _ := s.handler.chainSync.modeAndLocalHead()
 	return mode
 }
+func (s *Ethereum) Config() *ethconfig.Config {
+	return s.config
+}
 
 // Protocols returns all the currently configured
 // network protocols to start.

eth/gasestimator/gasestimator.go

@@ -42,8 +42,10 @@ type Options struct {
 	Chain  core.ChainContext   // Chain context to access past block hashes
 	Header *types.Header       // Header defining the block context to execute in
 	State  *state.StateDB      // Pre-state on top of which to estimate the gas
-
-	ErrorRatio float64 // Allowed overestimation ratio for faster estimation termination
+	// This flag whether determines we should make the copy of the opts.State or not.
+	// In the case of bundling transactions, we don't need to make a new copy of opts.State
+	IsNotCopyStateDB bool
+	ErrorRatio       float64 // Allowed overestimation ratio for faster estimation termination
 }
 
 // Estimate returns the lowest possible gas limit that allows the transaction to
@@ -206,13 +208,19 @@ func execute(ctx context.Context, call *core.Message, opts *Options, gasLimit ui
 // call invocation.
 func run(ctx context.Context, call *core.Message, opts *Options) (*core.ExecutionResult, error) {
 	// Assemble the call and the call context
+	var dirtyState *state.StateDB
+	if opts.IsNotCopyStateDB {
+		dirtyState = opts.State
+	} else {
+		dirtyState = opts.State.Copy()
+	}
 	var (
 		msgContext = core.NewEVMTxContext(call)
 		evmContext = core.NewEVMBlockContext(opts.Header, opts.Chain, nil)
 
-		dirtyState = opts.State.Copy()
-		evm        = vm.NewEVM(evmContext, msgContext, dirtyState, opts.Config, vm.Config{NoBaseFee: true})
+		evm = vm.NewEVM(evmContext, msgContext, dirtyState, opts.Config, vm.Config{NoBaseFee: true})
 	)
+
 	// Monitor the outer context and interrupt the EVM upon cancellation. To avoid
 	// a dangling goroutine until the outer estimation finishes, create an internal
 	// context for the lifetime of this method call.